Introduction
Pregnancy is a miraculous journey where a tiny cell transforms into a fully-formed human being. As a parent-to-be, you might be curious about the changes occurring inside your womb. Thanks to medical advancements, we now have real pictures of fetal development week by week that can give you a glimpse into this amazing process. From the first few cells to a fully developed baby, these images capture the incredible transformations that take place during each week of pregnancy. In this post, we’ll take a closer look at these images and explore the amazing journey of fetal development.
Week 1-4
During the first four weeks of pregnancy, development is just beginning. At this stage, the fertilized egg has implanted in the uterus and started to divide rapidly. By the end of the first week, the embryo is a ball of cells known as a blastocyst. As the second week begins, the blastocyst continues to divide and starts to form two distinct layers – the inner cell mass and the outer layer that will eventually become the placenta.
By week three, the inner cell mass has started to form into the three layers that will eventually give rise to all of the body’s organs and tissues. These layers are known as the endoderm, mesoderm, and ectoderm. The endoderm will eventually form the digestive and respiratory systems, while the mesoderm will give rise to the muscles, bones, and circulatory system. The ectoderm will form the skin, hair, and nervous system.
By week four, the embryo has grown to about the size of a poppy seed and the neural tube – which will eventually become the brain and spinal cord – begins to form. The heart also starts to beat at this stage, although it is still very primitive and only has two chambers. The embryo also starts to develop limb buds, which will eventually become the arms and legs.
Overall, the first four weeks of fetal development are crucial for laying the groundwork for all future growth and development. While the embryo is still very small and not yet recognizable as a human being, these early stages are incredibly important for ensuring that the baby develops properly and is healthy throughout its life.
Week 5-8
Week 5-8:
During weeks 5-8 of fetal development, the embryo starts to take on a more recognizable shape. At this point, the head begins to take on a more rounded shape, and the brain, facial features, and internal organs begin to develop. The eyes, ears, and nose also begin to form, and the arms and legs become more defined.
By week 8, the embryo is about the size of a kidney bean and is officially called a fetus. The face is more human-like, and the eyes are visible, though they are still covered by a membrane. The arms and legs have grown longer, and the fingers and toes are starting to form. The heart is beating and can be seen on an ultrasound.
During this period, the fetus is also developing its reproductive organs, though it is still too early to determine the sex. The placenta is also forming, which will provide the fetus with the nutrients and oxygen it needs to grow.
Overall, weeks 5-8 are a crucial period of fetal development, as many of the major organs and structures are beginning to form. It is important for the mother to take good care of herself during this time, avoiding alcohol, tobacco, and other harmful substances that could interfere with the development of the fetus.
Week 9-12
Week 9-12 marks the end of the embryonic period and the beginning of the fetal period. At this stage, the fetus is about 2.5 inches long and weighs approximately 0.5 ounces. The baby’s facial features are becoming more defined, and the eyes are moving closer together. The ears are also moving into their proper position on the sides of the head.
The baby’s brain is rapidly developing, and the nerve cells are multiplying at a staggering rate of 250,000 per minute. The fetus can now move its arms and legs, and the joints are becoming more flexible. The fingers and toes are also beginning to separate, and the nails are starting to form.
The digestive system is also starting to develop, and the liver is producing bile. The kidneys are functioning and producing urine, which is released into the amniotic fluid. The fetal heartbeat can now be heard using a Doppler ultrasound machine.
During this stage, the fetus is still very small and delicate, which means that the mother must take extra care to ensure a healthy pregnancy. This includes eating a healthy diet, getting regular exercise, and avoiding harmful substances such as alcohol and tobacco.
As the weeks progress, the fetus will continue to grow and develop at an incredible pace. By the end of the 12th week, the baby will be fully formed, and all of its organs and systems will be in place. The next few months will be focused on growth and development, as the baby prepares for life outside the womb.
Week 13-16
Week 13:
During the 13th week of pregnancy, the baby’s vocal cords are beginning to form, which means that they can hiccup! They are also starting to grow hair all over their body, called lanugo, which helps to regulate their body temperature. At this point, the baby is about the size of a lemon and can wiggle their fingers and toes.
Week 14:
By week 14, the baby’s facial expressions are becoming more developed, and they can even frown or squint. Their kidneys are starting to produce urine, which they will eventually release into the amniotic fluid. The baby is now roughly the size of a peach and can move their arms and legs around.
Week 15:
During week 15, the baby’s limbs are getting longer and more proportional to their body, and they can even make a fist. They are also developing taste buds, which means that they can start to taste the amniotic fluid. At this stage, the baby is about the size of an apple and can even sense light through their eyelids.
Week 16:
At 16 weeks, the baby’s eyes are moving closer together, and their ears are moving to their final position on the sides of their head. They are also starting to develop more complex movements, like sucking their thumb or making facial expressions. The baby is now about the size of an avocado and can even hear their mother’s voice and heartbeat.
Week 17-20
During weeks 17-20, your baby will be about the size of a turnip! At this point, their skeleton is starting to harden and their body is becoming more proportional. Their skin is still thin and translucent, but their eyes are beginning to move from the sides of their head to the front. Your baby’s ears are also moving into their final position on the sides of their head.
By week 18, your baby’s nervous system is developing rapidly. Their brain is growing quickly and they are starting to develop their own unique fingerprints. Your baby is also starting to develop reflexes, like swallowing and sucking. Around this time, you may be able to feel your baby’s movements for the first time, although it may still be a few weeks before they are strong enough for others to feel.
By week 19, your baby’s skin is becoming less transparent and they are starting to develop a layer of fat under their skin. This layer of fat will help regulate their body temperature and provide cushioning. Your baby’s hair is also starting to grow, and they may even have a full head of hair by birth!
As you approach week 20, your baby is about the size of a banana. They are becoming more active and coordinated, and their movements are becoming stronger. At this point, your baby is also developing their sense of taste and may even be able to taste the amniotic fluid that surrounds them.
Overall, weeks 17-20 are a time of rapid development for your growing baby. Keep taking care of yourself and your little one, and soon enough you’ll be holding your precious bundle of joy in your arms.
Week 21-24
Week 21-24
During this stage of pregnancy, the fetus is about the size of a large mango, measuring about 10.5 to 11.8 inches in length and weighing around 12.7 to 20.8 ounces. At this point, the fetus’s skin is still translucent, but it is gradually becoming more opaque. The bones in the ears are starting to harden, and the fetus is now able to hear some sounds from the outside world. The lungs are also developing rapidly, and the fetus is practicing breathing movements by inhaling amniotic fluid.
The brain is developing at an incredible rate, with the cerebral cortex now controlling the senses of touch, taste, smell, and hearing. The fetus’s eyes are formed, and the retinas are starting to develop. This means that the fetus’s vision is starting to improve, and it can now distinguish between light and dark. The digestive system is also growing, and the fetus is now swallowing amniotic fluid, which helps to develop the digestive tract.
The fetus’s movements are becoming more coordinated, and it can now grasp, kick, and even hiccup. The mother may start to feel more distinct movements at this stage, which can be an exciting milestone in the pregnancy. As the fetus grows, it will soon start to run out of room in the uterus, so its movements may become more subdued in the coming weeks.
Overall, the 21-24 week period is a crucial stage of fetal development, with significant progress being made in the growth and maturation of many organs and systems. It is essential for the mother to continue to take care of herself and her growing baby during this time, ensuring that she gets enough rest, eats a healthy diet, and attends regular prenatal check-ups.
Week 25-28
Week 25-28 marks the beginning of the third trimester. At this stage, the fetus is about 14.8 inches long and weighs around 2.2 pounds. The baby’s brain continues to develop rapidly, and the lungs are maturing, preparing for the first breath. The eyes can now open and close, and the baby can see light filtering through the womb. The fetus can also hear sounds from outside the womb, including the mother’s voice and heartbeat.
During these weeks, the baby’s movements become more coordinated, and the mother can feel more distinct kicks and jabs. The baby’s skin becomes less translucent and starts to develop a more opaque appearance. The baby’s bones are also beginning to harden, and the nervous system is becoming more complex.
As the due date approaches, the baby will continue to gain weight and grow in size. The mother may experience more discomfort due to the baby’s movements and the increasing pressure on her organs. It’s essential to continue regular prenatal appointments and to follow any recommendations from the healthcare provider to ensure a healthy pregnancy and delivery.
Week 29-32
During week 29, the baby’s body is becoming more proportionate. The head is still larger than the rest of the body, but not as dramatically as in previous weeks. The baby is approximately 15.2 inches long and weighs about 2.5 pounds. The baby’s bones are fully formed, but they are still soft and pliable. The baby’s eyes can now open and close, and they have eyelashes and eyebrows.
By week 30, the baby’s brain is developing rapidly. The baby’s eyes can distinguish between light and dark, and their irises now have pigmentation. The baby is approximately 16.2 inches long and weighs about 3.5 pounds. The baby’s lungs are not yet fully developed, but they are producing surfactant, which will help them expand and contract properly after birth.
During week 31, the baby’s movements become more coordinated. They can now turn their head from side to side and may even respond to sounds outside the womb. The baby is approximately 16.7 inches long and weighs about 3.75 pounds. The baby’s bones are now hardening, but they are still somewhat pliable.
By week 32, the baby’s skin is becoming less translucent and more opaque. The baby is approximately 17.6 inches long and weighs about 4.5 pounds. The baby’s lungs are continuing to mature, and they are now capable of breathing air. The baby’s digestive system is also maturing, and they are practicing swallowing and digesting amniotic fluid.
Week 33-36
As the third trimester of pregnancy continues, your baby is getting bigger and stronger every day. At week 33, your baby is about the size of a pineapple, weighing around 4 pounds and measuring about 17 inches long. Your baby’s bones are hardening, and their nervous system is continuing to develop.
By week 34, your baby’s lungs are almost fully developed, and they are practicing breathing movements. They may also be able to recognize your voice and respond to it. At this stage, your baby is about the size of a cantaloupe, weighing around 4.5 pounds and measuring about 18 inches long.
Week 35 marks the beginning of the “late preterm” stage, meaning that if your baby were to be born now, they would have a good chance of survival with medical intervention. Your baby is now about the size of a honeydew melon, weighing around 5.5 pounds and measuring about 19 inches long. They are continuing to gain weight and develop their immune system.
Finally, at week 36, your baby is considered full-term, meaning that they are fully developed and ready to be born. Your baby is now about the size of a head of romaine lettuce, weighing around 6 pounds and measuring about 20 inches long. They may be in the head-down position in preparation for birth, and their skin is becoming smoother and less wrinkled.
Week 37-40
During weeks 37-40, the baby is considered full-term and is ready to be born at any time. At this stage, the baby weighs around 6-9 pounds and measures about 19-21 inches in length. The baby’s skin becomes less wrinkled as they accumulate fat under the skin, and their limbs become chubby. The baby’s lungs are fully developed, and they are practicing breathing movements by inhaling and exhaling amniotic fluid.
The baby’s head size is about the same circumference as their abdomen, and their skull bones are not yet fused to allow for easier passage through the birth canal. The baby’s digestive system is also fully developed, and they have a meconium stool stored in their intestines, which is the first stool the baby will pass after birth.
During these final weeks, the baby is mainly gaining weight and preparing for birth. The mother may experience more Braxton Hicks contractions, which are practice contractions that help the uterus prepare for labor. The mother may also experience more discomfort as the baby’s head moves further down into the pelvis. Overall, these last few weeks of pregnancy are exciting as the baby is ready to make their grand entrance into the world.
Conclusion
In conclusion, fetal development week by week serve as a testament to the incredible journey that takes place inside a mother’s womb. From the early stages of single-celled zygotes to fully-formed infants ready for the outside world, the growth and transformation of a developing fetus is nothing short of miraculous. The images we’ve shared here provide a rare glimpse into this process, and we hope they’ve helped you gain a deeper appreciation for the complexity and beauty of human life. Whether you’re a parent-to-be or simply curious about the wonders of biology, we encourage you to continue exploring and learning about this fascinating topic. Thank you for joining us on this journey!